Not all charters are created equal. The quality of the schools fluctuates widely by state. (Our ability even to evaluate charters varies greatly, too, depending on who performs the evaluations, what methods they use, and which schools they examine.) A few jurisdictions â€” Massachusetts, New York, Illinois â€” are sparing in their distribution of charter contracts and, for the most part, check carefully to determine whether organizations that get the green light have what it takes to succeed. As a result, these states have relatively few charter schools, but their performance is impressive. Meanwhile, states like Arizona, Ohio, Texas, and California confer charters on nearly everyone who applies; as a consequence, they now have many charter schools but also wide discrepancies in charter quality and performance ( tending, however, toward the mediocre). So even as Stanford economist Caroline Hoxby reports solid gains by charter pupils in New York City, Ohio’s school-rating system for academic year 2008-9 showed that just 16% of Buckeye charter pupils were in schools rated “excellent” or “effective,” while 55% of them attended schools on “academic watch” or in “academic emergency.” And Texas is home to some of America’s strongest charters â€” Houston is ground zero for KIPP and the “YES Prep” network â€” but also dozens of the weakest.

In other words, in liberal states where the teachers’ unions have clout and charters are greeted warily, the charter schools that do exist are excellent. In conservative states where charters are greeted with open arms, they’re mostly mediocre. There’s a lesson in there somewhere.